Apparatus and method for controlling reverse-link data transmission rate during handoff

ABSTRACT

Method and apparatus for controlling data transmission rate in a wireless communication system during handoff comprises a terminal recognizing an active set comprising a serving base station and at least one non-serving base station with respect to the terminal communicating with the network at a first data transmission rate, receiving a first rate control parameter from the serving base station and a second rate control parameter from the at least one non-serving base station, wherein the first and second rate control parameters are associated with determination of a second data transmission rate of the terminal during the handoff and determining the second data transmission rate in response to the first and the second rate control parameters, wherein the second data transmission rate is one of increased rate, decreased rate and same rate from the first data transmission rate.

CROSS REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. §119(a), this application claims the benefit ofthe Korean Applications Nos. 2003-27199 filed on Apr. 29, 2003 and2003-76562 filed on Oct. 31, 2003, the contents of which are herebyincorporated by reference herein in their entirety.

This application also claims the benefit of U.S. Provisional ApplicationSer. Nos. 60/514,383 filed on Oct. 24, 2003, 60/515,897 filed on Oct.29, 2003, and 60/516,232, filed on Oct. 30, 2003, the contents of whichare hereby incorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a mobile communications system, andmore particularly, to a method and apparatus for controlling a datatransmission rate for a reverse link, in which a traffic-to-pilot powerratio is used to set the data transmission rate of a terminal underhandoff.

2. Discussion of the Related Art

In the world of cellular telecommunications, those skilled in the artoften use the terms 1G, 2G, and 3G. The terms refer to the generation ofthe cellular technology used. 1G refers to the first generation, 2G tothe second generation, and 3G to the third generation.

1G is used to refer to the analog phone system, known as an AMPS(Advanced Mobile Phone Service) phone systems. 2G is commonly used torefer to the digital cellular systems that are prevalent throughout theworld, and include CDMAOne, Global System for Mobile communications(GSM), and Time Division Multiple Access (TDMA). 2G systems can supporta greater number of users in a dense area than can 1G systems.

3G is commonly used to refer to the digital cellular systems currentlybeing developed. Recently, third-generation (3G) CDMA communicationsystems have been proposed including proposals, such as cdma2000 andW-CDMA. These 3 G communication systems are conceptually similar to eachother with some significant differences.

A cdma2000 system is a third-generation (3G) wideband; spread spectrumradio interface system which uses the enhanced service potential of CDMAtechnology to facilitate data capabilities, such as Internet andintranet access, multimedia applications, high-speed businesstransactions, and telemetry. The focus of cdma2000, as is that of otherthird-generation systems, is on network economy and radio transmissiondesign to overcome the limitations of a finite amount of radio spectrumavailability.

Referring to FIG. 1, a wireless communication network architecture 1 isillustrated. A subscriber uses a Mobile Station 2 to access networkservices. The Mobile Station 2 may be a portable communications unit,such as a hand-held cellular phone, a communication unit installed in avehicle, or a fixed-location communications unit.

The electromagnetic waves from the Mobile Station 2 are transmitted bythe Base Transceiver System (BTS) 3 also known as node B. The BTS 3consists of radio devices such as antennas and equipment fortransmitting radio waves. The Base Station Controller (BSC) 4 receivesthe transmissions from one or more BTS's. The BSC 4 provides control andmanagement of the radio transmissions from each BTS 3 by exchangingmessages with the BTS and the Mobile Switching Center (MSC) 5 orInternal IP Network. The BTS's 3 and BSC 4 are part of the Base Station(BS) 6.

The BS 6 exchanges messages with and transmits data to a CircuitSwitched Core Network (CSCN) 7 and Packet Switched Core Network (PSCN)8. The CSCN 7 provides traditional voice communications and the PSCN 8provides Internet applications and multimedia services.

The Mobile Switching Center (MSC) 5 portion of the CSCN 7 providesswitching for traditional voice communications to and from a MobileStation 2 and may store information to support these capabilities. TheMSC 2 may be connected to one of more BS's 6 as well as other publicnetworks, for example a Public Switched Telephone Network (PSTN) (notshown) or Integrated Services Digital Network (ISDN) (not shown). AVisitor Location Register (VLR) 9 is used to retrieve information forhandling voice communications to or from a visiting subscriber. The VLR9 may be within the MSC 5 and may serve more than one MSC.

A user identity is assigned to the Home Location Register (HLR) 10 ofthe CSCN 7 for record purposes such as subscriber information, forexample Electronic Serial Number (ESN), Mobile Directory Number (MDR),Profile Information, Current Location, and Authentication Period. TheAuthentication Center (AC) 11 manages authentication information relatedto the Mobile Station. The AC 11 may be within the HLR 10 and may servemore than one HLR. The interface between the MSC 5 and the HLR/AC 10, 11is an IS-41 standard interface 18.

The Packet Data Serving Node (PDSN) 12 portion of the PSCN 8 providesrouting for packet data traffic to and from Mobile Station. The PDSN 12establishes, maintains, and terminates link layer sessions to the MobileStation's 2 and may interface with one of more BS 6 and one of more PSCN8.

The Authentication, Authorization and Accounting (AAA) 13 Serverprovides Internet Protocol authentication, authorization and accountingfunctions related to packet data traffic. The Home Agent (HA) 14provides authentication of MS 2 IP registrations, redirects packet datato and from the Foreign Agent (FA) 15 component of the PDSN 8, andreceives provisioning information for users from the AAA 13. The HA 14may also establish, maintain, and terminate secure communications to thePDSN 12 and assign a dynamic IP address. The PDSN 12 communicates withthe AAA 13, HA 14 and the Internet 16 via an Internal IP Network.

FIG. 2 illustrates a data link protocol architecture layer 20 for awireless network. It includes an upper layer 60, a link layer 30 and aphysical layer 21.

The upper layer 60 contains three basis services; voice services 62,data services 61 and signaling 70. Voice services 62 include PSTNaccess, mobile-to-mobile voice services, and Internet telephony. Dataservices 61 are services that deliver any form of data on behalf of amobile end user and include packet data applications such as IP service,circuit data applications such as asynchronous fax and B-ISDN emulationservices, and SMS. Signaling 70 controls all aspects of mobileoperation.

The Link Layer 30 is subdivided into the Link Access Control (LAC)sublayer 32 and the Medium Access Control (MAC) sublayer 31. The linklayer 30 provides protocol support and control mechanisms for datatransport services and performs the functions necessary to map the datatransport needs of the upper layer 60 into specific capabilities andcharacteristics of the physical layer 21. The Link Layer 30 may beviewed as an interface between the upper layers and the Physical Layer20.

The separation of MAC 31 and LAC 32 sublayers is motivated by the needto support a wide range of upper layer 60 services, and the requirementto provide for high efficiency and low latency data services over a wideperformance range (from 1.2 Kbps to greater than 2 Mbps). Othermotivators are the need for supporting high QoS delivery of circuit andpacket data services, such as limitations on acceptable delays and/ordata BER (bit error rate), and the growing demand for advancedmultimedia services each service having a different QoS requirements.

The LAC sublayer 32 is required to provide a reliable, in-sequencedelivery transmission control function over a point-to-point radiotransmission link 42. The LAC sublayer 32 manages point-to pointcommunication channels between upper layer 60 entities and providesframework to support a wide range of different end-to-end reliable linklayer 30 protocols.

The MAC sublayer 31 facilitates complex multimedia, multi-servicescapabilities of 3G wireless systems with Quality of Service (QoS)management capabilities for each active service. The MAC sublayer 31provides procedures for controlling the access of data services (packetand circuit) to the physical layer 21, including the contention controlbetween multiple services from a single user, as well as betweencompeting users in the wireless system. The MAC sublayer 31 alsoprovides for reasonably reliable transmission over the radio link layerusing a Radio Link Protocol (RLP) 33 for a best-effort level ofreliability. Signaling Radio Burst Protocol (SRBP) 35 is an entity thatprovides connectionless protocol for signaling messages. Multiplexingand Quality of Service (QoS) Control 34 is responsible for enforcementof negotiated QoS levels by mediating conflicting requests fromcompeting services and the appropriate prioritization of accessrequests.

The Physical Layer 20 is responsible for coding and modulation of datatransmitted over the air. The Physical Layer 20 conditions digital datafrom the higher layers so that the data may be transmitted over a mobileradio channel reliably.

The Physical Layer 20 maps user data and signaling, which the MACsublayer 31 delivers over multiple transport channels, into a physicalchannels and transmits the information over the radio interface. In thetransmit direction, the functions performed by the Physical Layer 20include channel coding, interleaving, scrambling, spreading andmodulation. In the receive direction, the functions are reversed inorder to recover the transmitted data at the receiver.

An optimum rate of data transmission in the reverse link of a mobilecommunications system, for example, a first-evolution data-optimized(1xEV-DO) system, is determined with respect to the rise-over-thermal ofa given base station 6. The rise-over-thermal is a dynamic receptioncharacteristic defined as total power of signal of total power receivedat the base station 6, from all active mobile stations 2 (also referredto as terminals), and the thermal noise detected at the base station. Inother words, the rise-over-thermal is the summed signal power of allactive-terminal signals received at the base station 6, which is afunction of reverse activity, i.e., the number and transmission rate ofactive terminals 2 operating in connection with the base station.

Ideal reverse-link conditions result when the rise-over-thermal at thebase station 6 is maintained at a constant level despite fluctuations inreverse activity, such that the rise-over-thermal is a function of thevarious transmission rates for a given number of active terminals 2.Thus, the system compensates by controlling inter alia the datatransmission rate of the reverse link of each terminal 2.

To enable such control, the rise-over-thermal is compared with athreshold value, and based on the comparison results, an active terminal2 is requested to increase or decrease its transmission rate whencommunicating with the base station 6. That is, the transmission ratemay be increased when the rise-over-thermal is below the threshold, butif the rise-over-thermal exceeds the threshold, it is necessary todecrease the transmission rate.

FIG. 3 illustrates a reverse-link transmission rate control method 50according to a related art. As illustrated in FIG. 3, one base station 6and one active terminal 2 of a 1xEV-DO system act together in each frameto set an optimum rate for the next frame of the reverse link.

In step S52, the base station 6 measures the rise-over-thermal (RoT)produced by the cumulative effect of all reverse-link data signalspower. With the rise-over-thermal thus determined, the base station 6generates, in step S54, a reverse activity bit (RAB) as part of aninstruction word for use by a terminal 2. As described above, the RABvalue or parameter is set according to a comparison of therise-over-thermal and a predetermined threshold value, whereby one valuewould instruct the terminal 2 to decrease its transmission rate, andanother value would instruct the terminal to increase its transmissionrate.

In step S56, the base station 6 transmits the reverse activity bit toall active terminals 2 within active sectors, or all terminalstransmitting data on the reverse link via a random access channel, whichis a common channel. Thus, all terminals 2 simultaneously receive aninstruction word containing the same reverse activity bit for a givenframe, such that all terminals are simultaneously instructed to increaseor decrease their set rate of data transmission for the next frame.

In step S58, a terminal 2 receiving the reverse activity bit performs acompliance test to determine whether the data transmission rate shouldbe changed based on the received bit. The terminal 2 considers the datarate of the current frame of the reverse link transmission and, using apredetermined algorithm, determines either to comply with theinstruction from the base station 6 and change the transmission rateaccordingly or to ignore the instruction and set the transmission rateof the next frame equal to that of the current frame. In step S60, theterminal 2 sets the data transmission rate of the next frame.

In the aforementioned method 50 according to the related art, thereverse activity bit is generated based solely on the rise-over-thermalmeasured at the base station 6 and the bit is simultaneously transmittedas a single command to all active terminals 2 within active sectors. Inother words, there is no consideration of the status of any one of theterminals 2. There are inherent disadvantages in this method.

For any given terminal 2, the only option other than complying with theinstruction from the base station 6 is to ignore the instruction andmaintain the current data transmission rate. Therefore, since theterminal 2 cannot consider its current status in determining whether tochange its transmission rate, reverse-link transmission efficiency tendsto suffer.

On the other hand, any given terminal 2 receiving a reverse activity bitmay comply with the corresponding instruction or ignore the instructionbased on the results of its own compliance test, and, therefore, may notchange its transmission rate. Therefore, effective regulation of therise-over-thermal by a base station 6 is hindered, which also degradesreverse-link transmission efficiency.

SUMMARY OF THE INVENTION

The present invention is directed to a method and apparatus forcontrolling a data transmission rate for a reverse link, in which atraffic-to-pilot ratio is used to set the data transmission rate of aterminal under handoff.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. Theobjectives and other advantages of the invention will be realized andattained by the structure particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, the presentinvention is embodied in a mobile communication device that utilizes atraffic-to-pilot power ratio (T/P) to set a data transmission rate forterminals in communication with one or more base stations duringhandoff. Specifically, the status of terminal resources and the channelstatus of the reverse link are considered when a base station generatesdata transmission control information for transmission to a plurality ofterminals.

In one aspect of the invention, a method is provided for controlling thedata transmission rate in a mobile communication system during handofffor communicating between a network and a terminal. The method includesthe steps of determining an active set with respect to a terminalcommunicating with a base station at a first transmission rateassociated with a first T/P, transmitting terminal status to a servingbase station, generating a rate control parameter for transmission froma serving base station to the terminal, generating a rate controlparameter for transmission from a non-serving base station to theterminal, receiving the rate control parameters at the terminal,determining whether to decode the rate control parameters, anddetermining and setting a new data transmission rate for the terminalbased on either the first T/P or a new T/P based on the rate controlparameters.

Preferably, the terminal status information includes an indication ofavailable terminal power and the amount of data to be transmitted. Ingenerating reverse-link data transmission rate control parameters, suchas a rate control bit (RCB), for a terminal having data to transmit,each base station considers its rise-over-thermal and a channel statusof the reverse link. The RCB can be transmitted on a forward-link commonchannel, and dedicated ACK/NACK information for reverse-link packet datacan be transmitted on a forward-link packet data receptionacknowledgement channel, which may be multiplexed with the forward-linkcommon channel.

In a preferred embodiment, the terminal decodes an RCB after receivingan ACK signal from any base station or after transmitting the lastsubpacket. It is contemplated that the terminal may only decode the RCBafter simultaneously receiving an ACK signal from the base stationtransmitting the RCB.

A terminal sets the authorized traffic-to-pilot power ratio based on theRCB information received from the base stations and thereby establishesan appropriate setting for the reverse-link data transmission rate. Withan authorized traffic-to-pilot power ratio thus determined, thereverse-link data transmission rate can be set accordingly.

In a preferred embodiment, the terminal decreases the authorizedtraffic-to-pilot power ratio if a decrease instruction is contained inthe RCB information received from a non-serving base station. If nodecrease instruction is contained in the RCB information received from anon-serving base station, the terminal sets the authorizedtraffic-to-pilot power ratio based on RCB information received from theserving base station.

The terminal maintains (holds) the current authorized traffic-to-pilotpower ratio if the RCB information received from the serving basestation is a hold instruction. The terminal increases the authorizedtraffic-to-pilot power ratio if the RCB information received from theserving base station is an increase instruction.

The terminal may also receive and process messages from a serving basestation indicating that a specific data transmission rate be set. Thespecific rate message will override processing of an RCB from theserving base station such that, in the absence of an RCB from anon-serving base station indicating a decrease in the transmission rate,the transmission rate is set to the specified rate. It is furthercontemplated that the specific rate message may also override processingof RCBs from non-serving base stations such that the transmission rateis set to the specified rate irrespective of any RCBs received.

In another aspect of the invention, an apparatus is provided forcontrolling the data transmission rate in a mobile communication systemduring handoff for communicating between a network and a terminal. Theapparatus determines an active set with respect to a terminalcommunicating with a base station at a first transmission rateassociated with a first T/P, transmits terminal status to a serving basestation, receives a rate control parameter from a serving base stationand a rate control parameter from a non-serving base station, determineswhether to decode the rate control parameters, and determines and sets anew data transmission rate for the terminal based on either the firstT/P or a new T/P based on the rate control parameters. The apparatus mayalso receive and process messages from a serving base station indicatinga specific data transmission rate be set and override the processing ofrate control parameters from the serving base station and non-servingbase stations.

It is to be understood that both the foregoing explanation and thefollowing detailed description of the present invention are exemplaryand illustrative and are intended to provide further explanation of theinvention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings

FIG. 1 illustrates a wireless communication network architecture.

FIG. 2 illustrates a data link protocol architecture layer for awireless network.

FIG. 3 illustrates a flowchart of a method for controlling areverse-link data transmission rate according to a related art.

FIG. 4 illustrates a flowchart of a method for controlling areverse-link data transmission rate according one embodiment of thepresent invention.

FIG. 5 illustrates a flowchart of a method for setting an authorizedtraffic-to-pilot power ratio based on RCBs received at a terminal underhandoff according to one embodiment of the present invention.

FIG. 6 illustrates a flowchart of a method for setting an authorizedtraffic-to-pilot power ratio based on RCBs received at a terminal underhandoff according to another embodiment of the present invention.

FIG. 7 illustrates a block diagram of a channel structure fortransmitting a plurality of rate control bits and a correspondingplurality of ACK/NACK bits, to implement a method of the presentinvention.

FIG. 8 illustrates a block diagram of mobile station according to thepreferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention relates to a method and apparatus for controllinga data transmission rate for a reverse link, in which a traffic-to-pilotratio is used to set the data transmission rate of a terminal underhandoff. Although the invention is described herein with regard tocontrolling a data transmission rate of a terminal under handoff, it iscontemplated that the invention may be utilized any time it is desiredto control the data transmission rate of a first device in communicationwith one or more other devices by considering the status of deviceresources and the status of the link over which the devices communicate.

Wherever possible, the same reference numbers are used throughout thedrawings to refer to the same or like parts. To aid describing thepresent invention, certain parameter names are being used to describethe channels, messages and variables communicated between terminals 2and base stations 6. It should be noted that such parameter names arefor illustration purposes only, and that other names may be used todescribe the same or similar function.

Referring to FIG. 4, a method 100 for controlling a reverse-link datatransmission rate in accordance with one embodiment of the presentinvention is illustrated. As illustrated, a single base station 6communicates with one of a plurality of terminals 2. The method 100includes transmitting terminal status to a base station 6 (S102),generating a rate control bit (RCB) in the base station 6 (S104),transmitting the RCB to a terminal 2 (S106), receiving the RCB in theterminal (S108), determining whether the RCB is to be decoded (S110),setting a new T/P value (S112) if the RCB is decoded, and setting a newdata transmission rate (S114) based on the T/P value. In a handoffstate, the method 100 is applicable to both a serving base station 6 andone or more non-serving base stations communicating with a plurality ofterminals 2.

In reverse-link data transmission, a terminal 2 typically initiatestransmission independent of any base station 6 rather than a basestation initiating transmission. Thus, in determining the initialtransmission rate, a terminal 2 having data to transmit to a basestation 6 on a reverse link performs one of two processes.

In one process, data is initially transmitted at the lowest datatransmission rate currently supportable by the terminal 2, for example9.6 kbps. In the other process, data is transmitted at a rate determinedthrough negotiation between a terminal 2 and base station 6, for example38.4 kbps. The terminal 2 sets the transmission rate after negotiationwith the base station 6 with regard to the optimum transmission rate. Inboth processes, the data rate is set without any base station 6 control.

In step S102, at the outset of reverse-link data transmission at a giveninitial transmission rate as determined above, the terminal 2 transmitsa terminal status to the base station 6. The terminal status includes atleast one bit, for example a terminal status information bit, informingthe base station 6 of the status of the transmitting terminal 2.Preferably, the terminal status is based on parameters affecting adesirable transmission rate such as the amount of reserve battery poweravailable, buffer states, and the amount of data to be sent.

For subsequent data transmission, the reverse-link transmission rate isdetermined, or at least affected, by the base station 6. In the eventthat the terminal 2 transmits data at a rate higher than the highestindependent data transmission rate authorized at the time of callinitiation, the base station 6 controls the transmission rate.

In step S104, the base station 6 generates at least one bit ofreverse-link data transmission rate control information in the form ofan RCB dedicated to the terminal 2. In step S106, the base station 6transmits the RCB to the terminal 2, either periodically oraperiodically, by assigning a minimum transmission time unit, forexample 20 ms, during which the base station performs at most one RCBtransmission.

In generating a dedicated RCB for the terminal 2, the base station 6considers a variety of factors including the channel status of thereverse links, the terminal status information bits, the status ofresources and the forms of their services, and the rise-over-thermal. Aserving base station 6 uses these factors to determine whether the datatransmission rate of the terminal 2 should be increased, decreased, ormaintained (held at the current rate). Non-serving base stations 6 usethese factors to determine whether or not the data transmission rate ofthe terminal 2 should be decreased.

Furthermore, the base station 6 may also transmit an RCB indicating adecrease in the data transmission rate of the terminal 2 if a decreasedrate is required due to a reception failure of a subpacket from theterminal. Such a failure is indicated, at the time of transmission, by adedicated NACK bit for reverse packet data.

The RCB information may comprise more than one bit for use by thecorresponding terminal 2, but one bit is sufficient to indicate eitherof two or any of three states. In the event of a two-state RCB utilizinga single bit of RCB information, one logic state may indicate aninstruction to increase the data transmission rate of the terminal 2 andthe opposite logic state may indicate an instruction to decrease thedata transmission rate of the terminal 2. A third state, signifying ahold instruction to maintain the data transmission rate of the terminal2 maybe indicated by the absence of RCB information from the basestation 6.

Accordingly, the RCB information contains instruction information toincrement, decrement, or maintain the data transmission rate of theterminal 2 and thereby set the data transmission rate of the reverselink. A negotiation process between the base station 6 and terminal 2may be employed to set the size or number of increments/decrements to beexecuted for any one transmitted instruction.

In step S108, the base station 6 receives the transmitted RCB. In stepS110, the terminal 2 determines whether to decode the RCB.

When a terminal 2 receives RCBs from more than one active base station6, RCB decoding may not be required if the terminal receives NACKs fromall active base stations since the terminal cannot change the datatransmission rate for a re-transmission of the immediately precedingsubpacket. However, the terminal 2 is still required to decode the RCBsif the terminal can no longer re-transmit the subpacket, for example ifthe subpacket is a final subpacket such that a new packet is beingformed and transmitted. Therefore, if a terminal 2 receives an ACKsignal from any one of the active base stations 6 or the immediatelypreceding subpacket is a final subpacket, the terminal decodes allreceived RCBs.

If RCB decoding is required, the terminal 2 sets the authorizedtraffic-to-pilot power ratio (T/P) according to the decoded contents ofthe RCB in step S112. If no RCB decoding is required, the present valueof the T/P is not changed. In step S114, the new data transmission rateis set based on the T/P value.

The power control feature of a code division multiplex (CDMA) system,which defines the relationship between the T/P and data transmissionrate, facilitates setting the data transmission rate based on thesetting of a traffic-to-pilot power ratio. A CDMA system regulatestransmission power so that received signal power is relatively constantwhile meeting performance requirements and minimizing interference. Thepower control for a reverse link is achieved through the use of powerincrease commands and power decrease commands, to maintain constantreception power in the pilot channel of the reverse link (R-PICH).

To maintain constant reception power, a base station 6 sets a thresholdvalue, measures the received power of the R-PICH, compares the measuredpower with the threshold, and transmits a power increase or decreasecommand based on the results of the comparison. This power regulation ofthe R-PICH enables a similar regulation of other channels transmittedfrom the terminal 2, such as data channels and control channels, byestablishing a ratio of the transmission power of the other channel tothat of the R-PICH. This traffic-to-pilot power ratio is a value set tomeet a performance requirement of the channel and is determined by thedata rate, coding method, and modulation method.

The burst characteristic exhibited by data communication such asvideo-on-demand, audio-on-demand, and other web-based data is differentfrom that of an audio signal enabling voice communication. Therefore, achannel has been devised for the effective handling of such datasignals, referred to as packet data.

Most packet data is transmitted on a packet data channel which enableserror correction through a hybrid automatic repeat request technique,whereby a terminal 2 confirms proper reception of a transmitted packetso that improperly received packets may be retransmitted withoutinstruction from an upper layer. To avoid endless re-transmission of apacket, CDMA standards limit the number of re-transmissions.Furthermore, a packet may be divided into subpackets. Each subpacket hasa structure such that decoding any one subpacket is possible and thesuccess or failure of a transmission of any subpacket can be known.

In the cdma2000 system, the coding method and the modulating method arefixed for the reverse-link PDCH such that the T/P value of the R-PDCH isa function of the data transmission rate, as illustrated in the examplesof Table 1. It can be seen that the T/P value increases for higher datarates for a given reception performance since higher data rates resultin greater reception energy.

In the conventional transmission of reverse-link data, a terminal 2indicates the amount of data to be transmitted and the availabletransmission power and requests a data transmission rate. A base station6 considers the limitations of the reverse-link resources and authorizesa rate of no more than that of other terminals 2 in order to maintain abalance among the terminals under the control of the base station. Uponreception of the authorized data rate on a forward-link control channel,a terminal 2 transmits data on the R-PDCH using a data rate of no morethan the authorized data rate.

As can be seen in Table 1, since the data transmission rate and thetraffic-to-pilot power ratio have a linear relationship, assignment ofan authorized T/P defines the authorized data transmission rate.Therefore, an authorization by way of either a data transmission rate ora T/P value results in the terminal 2 transmitting on the R-PDCH at adata transmission rate less than or equal to the corresponding value.

TABLE 1 Data rate T/P 19.2 kbps 2.25 dB 40.8 kbps 5.5 dB 79.2 kbps 8.375dB 156 kbps 11.25 dB 309.6 kbps 12 dB 463.2 kbps 13.75 dB 616.8 kbps15.125 dB 924 kbps 17 dB 1,231.2 kbps 18.625 dB 1,538.4 kbps 20.125 dB

Authorization using a T/P, however, provides greater flexibility. Forexample, if transmitting on two R-PDCHs simultaneously, authorizationusing a T/P allows a base station 6 to dictate one T/P and a terminal 2to set data transmission rates within a range of power required fortransmission of the two R-PDCHs, provided that neither rate exceeds thatcorresponding to the authorized T/P.

As another example, if transmitting data traffic having disparateperformance requirements on one R-PDCH, as in the case of contrastingservice types, different T/P values may be applied depending on servicetype. T/P values for two such service types are illustrated in Table 2.A terminal 2 transmitting a frame of each service type transmits at adata transmission rate no higher than its corresponding rate.

TABLE 2 T/P for T/P for data frame of data frame of data rate service 1service 2 19.2 kbps 2.25 dB 4 dB 40.8 kbps 5.5 dB 7.25 dB 79.2 kbps8.375 dB 10.125 dB 156 kbps 11.25 dB 13 dB 309.6 kbps 12 dB 13.75 dB463.2 kbps 13.75 dB 15.5 dB 616.8 kbps 15.125 dB 16.875 dB 924 kbps 17dB 18.75 dB 1,231.2 kbps 18.625 dB 20.375 dB 1,538.4 kbps 20.125 dB21.875 dB

In the method 100 illustrated in FIG. 4, when a base station 6 providesan RCB to a terminal 2, the terminal first sets an authorized T/P andthen sets the data transmission rate based on the set T/P. As a result,the method 100 of the present invention provides greater flexibility forterminals 2 utilizing complex transmission schemes.

Referring to FIG. 5, a method 200 for setting an authorized T/P by aterminal 2 under handoff conditions is illustrated. The method 200includes receiving and decoding an RCB from a serving base station 6and, optionally, from one of more non-serving base stations (S202),determining if the RCB contains an instruction to decrease the datatransmission rate (S204), decreasing the T/P if a decrease instructionwas received (S206), determining if the RCB contains a hold instructionfrom a serving base station 6 (S208) if no decrease instruction wasreceived, maintaining the T/P if a hold instruction was received (S210),increasing the T/P if no hold instruction was received (S212), andsetting a new data transmission rate based on the T/P (S214).

A serving base station 6 may generate and transmit an RCB containing aninstruction to increase the data transmission rate, decrease the datatransmission rate, or hold the data transmission rate at the currentlevel. On the other hand, a non-serving base station 6 may generate andtransmit an RCB only when a decrease of the data transmission rate isrequired. However, in one embodiment, a non-serving base station 6 maygenerate and transmit an RCB containing a null instruction as anindication that no instruction to decrease the data transmission rate issent.

In step S202, the received RCB is decoded. It is assumed that theterminal 2 is required to decode all received RCBs, for example an ACKhas been received from at least one active base station 6 or theimmediately preceding subpacket was a final subpacket.

In step S204, it is determined if the received and decoded RCB containsan instruction to decrease the data transmission rate. If the RCBindicates a decrease in the transmission rate, the terminal 2 decreasesthe authorized traffic-to-pilot power ratio (T/P) in step S206.

As noted previously, even if a base station 6 transmits a NACK due toreception of no subpacket from the terminal 2, the base station cantransmit a decrease instruction when a decreased transmission rate isrequired. Therefore, when the terminal 2 receives a decrease instructionand a NACK from one base station 6 and an ACK from another base station,the terminal may still decrease the T/P in step S206.

However, in another embodiment, the T/P may be decreased in step S204only upon simultaneous receipt of an RCB containing an instruction todecrease the data transmission rate and an ACK from the same basestation 6. If the RCB containing an instruction to decrease the datatransmission rate is received with a NACK from the base station 6,processing continues as if no instruction to decrease the datatransmission rate was received from that base station.

If no decrease instruction was received, it is determined in step S208whether the RCB is from the serving base station 6 and the datatransmission rate control information indicates a hold instruction. If ahold instruction was received from the serving base station 6, theterminal 2 maintains the authorized T/P in step S210. In the absence ofa decrease instruction or a hold instruction from the serving basestation 6, the terminal 2 increases the T/P in step S212.

In step S214, a new data transmission rate is set based on the new T/P.The new transmission rate may be an increase over the previous rate, adecrease of the previous rate or the same as the previous rate.

As a terminal 2 transits between base stations 6, for example during acell-switching operation from one base station to another, the originalbase station continues to act as the serving base station only until thecell-switching operation is completed. Once the cell-switching operationis completed, the original base station 6 becomes a non-serving basestation. However, under soft handoff conditions, when there may be morethan one serving base station 6, the terminal 2 operates according tocommands only from the original base station and the setting of the T/Pis determined by considering only RCBs from the original serving basestation and non-serving base stations. Hence, an RCB from the newserving base station 6 is ignored until the cell-switching operation iscompleted.

FIG. 5 illustrates communication with a single terminal 2. In practice,however, a plurality of active terminals 2 are present in any one cell.A dedicated RCB may be generated and transmitted to each of a pluralityof terminals 2 via one common channel.

In other embodiments, the setting of the T/P based on an RCB from a basestation 6 may be overridden by a message provided aperiodically by aserving base station designating a specific data transmission rate. FIG.6 illustrates an embodiment in which a message designating a specificdata rate overrides all RCBs received, whether from a serving basestation 6 or a non-serving base station. In another embodiment, amessage designating a specific data rate overrides only an RCB receivedfrom a serving base station 6. Both embodiments are similar to method200.

The method 400 illustrated in FIG. 6 differs from the method 200illustrated in FIG. 5 in that, after the RCB is received and decoded instep S202, it is determined in step S403 if a designated rate messagewas received. If a designated rate message was received, the T/P is setbased on the indicated rate in step S405. If no designated rate messagewas received, it is determined in step S204 whether the RCB indicates adecrease in the data transmission rate.

The embodiment in which a message designating a specific data rateoverrides only an RCB received from the serving base station differsfrom the method 200 illustrated in FIG. 5 in that, after it isdetermined in step S204 that the received RCB indicates a decrease inthe transmission rate, it is further determined if the RCB indicating adecrease in the transmission rate was received from a non-serving basestation 6. If the RCB was received from a non-serving base station 6,the T/P is decreased in step S206. If the RCB to decrease the datatransmission rate was not received from a non-serving base station 6, itis determined if a designated rate message was received. If a designatedrate message was received, the T/P is set based on the indicated rate.If no designated rate message was received, the T/P is decreased in stepS206.

The embodiment in which a message designating a specific data rateoverrides only an RCB received from the serving base station furtherdiffers from the method 200 illustrated in FIG. 5 in that, after it isdetermined in step S204 that no RCB to decrease the data transmissionrate was received, it is determined if a designated rate message wasreceived. If a designated rate message was received, the T/P is setbased on the indicated rate. If no designated rate message was received,it is determined in step S208 whether the RCB was received from theserving base station 6 and indicates a “hold” instruction.

FIG. 7 illustrates a configuration of the common channel, referred tohere as a forward-link common rate control channel (F-CRCCH), which ismultiplexed with a forward-link common acknowledgment channel (F-CACKCH)for transmitting a corresponding plurality of ACK/NACK bits dedicated toreverse-link packets transmitted from the plurality of terminals 2. Thechannel configuration is achieved using a repeater, a signal pointmapping unit, and a channel gain unit for each dedicated RCB for aplurality (1 through N) of terminals 2 and corresponding elements foreach ACK/NACK bit. A long code is generated in a long code generator forinput to a decimator, and the decimator output is input to an offsetcalculator. First and second multiplexers are provided for multiplexingthe plurality RCB inputs and the plurality of ACK/NACK inputs,respectively, using the calculated offset from the offset calculator.The outputs of the first and second multiplexers are quadrature phaseshift keying signals XI and XQ.

FIG. 8 illustrates a block diagram of mobile station according to thepreferred embodiment of the present invention. The mobile station 500includes a processor (or digital signal processor) 510, RF module 535,power management module 505, antenna 540, battery 555, display 515,keypad 520, memory 530, SIM card 525 (which may be optional), speaker545 and microphone 550.

A user enters instructional information, such as a telephone number, forexample, by pushing the buttons of a keypad 520 or by voice activationusing the microphone 550. The microprocessor 510 receives and processesthe instructional information to perform the appropriate function, suchas to dial the telephone number. Operational data may be retrieved fromthe Subscriber Identity Module (SIM) card 525 or the memory module 530to perform the function. Furthermore, the processor 510 may display theinstructional and operational information on the display 515 for theuser's reference and convenience.

The processor 510 issues instructional information to the RF section535, to initiate communication, for example, transmit radio signalscomprising voice communication data. The RF section 535 comprises areceiver and a transmitter to receive and transmit radio signals. Anantenna 540 facilitates the transmission and reception of radio signals.Upon receiving radio signals, the RF module 535 may forward and convertthe signals to baseband frequency for processing by the processor 510.The processed signals would be transformed into audible or readableinformation outputted via the speaker 545, for example. The processor510 also performs the functions necessary to implement the methods 100,200, 300, 400 described herein in order to control a reverse-link datatransmission rate and set an authorized T/P by a terminal 2 underhandoff conditions.

By utilizing the methods of the present invention for controlling datatransmission rate for a reverse link, a terminal 2 can transmit dataeffectively by considering the status of resources and a channel statusof the reverse link to generate dedicated data transmission rate controlinformation in the base stations 6 for transmission to a plurality ofterminals. At the same time, the terminal 2 can eliminate the ambiguitysurrounding the rate control of a terminal in soft handoff mode. Themethods of the present invention provide greater flexibility forterminals utilizing complex transmission schemes, reduce therise-over-thermal of a base station 6, improve a reverse-linktransmission rate to enhance the efficiency of the reverse link, andprovide data transmission rate control information to respectiveterminals 2 based on the status of the reverse links and therise-over-thermal at the base station.

The foregoing embodiments and advantages are merely exemplary and arenot to be construed as limiting the present invention. The presentteaching can be readily applied to other types of apparatuses. Thedescription of the present invention is intended to be illustrative, andnot to limit the scope of the claims. Many alternatives, modifications,and variations will be apparent to those skilled in the art. In theclaims, means-plus-function clauses are intended to cover the structuredescribed herein as performing the recited function and not onlystructural equivalents but also equivalent structures.

1. A method of controlling data transmission rate in a terminal used ina wireless communication system comprising a network, the methodcomprising: providing data to the network at a first data transmissionrate, wherein the first data transmission rate is associated with afirst traffic-to-pilot power ratio; transmitting, to the network, astatus information bit on a reverse link to permit generation of a ratecontrol parameter based upon the status information bit; receiving therate control parameter from a serving base station and a non-servingbase station, wherein when the rate control parameter is received fromthe serving base station, the rate control parameter comprises a first,second, or third control state, the first control state indicatingincreasing the first traffic-to-pilot power ratio, the second controlstate indicating decreasing the first traffic-to-pilot power ratio, andthe third control state indicating maintaining the firsttraffic-to-pilot power ratio, and wherein when the rate controlparameter is received from the non-serving base station, the ratecontrol parameter comprises a fourth control state, the fourth controlstate indicating decreasing the first traffic-to-pilot power ratio;updating a second traffic-to-pilot power ratio of the terminal, bydecreasing the first traffic-to-pilot power ratio, when the rate controlparameter is received from the non-serving base station and includes thefourth control state indicating decreasing the first traffic-to-pilotpower ratio; updating the second traffic-to-pilot power ratio for theterminal using the rate control parameter received from the serving basestation as long as any rate control parameter that is received from thenon-serving base station does not include the fourth control stateindicating decreasing the first traffic-to-pilot power ratio; anddetermining a second data transmission rate for the terminal based uponthe second traffic-to-pilot power ratio.
 2. The method according toclaim 1, further comprising: determining a value of the statusinformation bit based on at least one of an amount of reverse linktransmission power, buffer status of the terminal, and an amount of datato be transmitted to the network.
 3. The method according to claim 1,wherein the status information bit is based on at least one of a bufferstatus of the terminal, and an amount of power available to theterminal.
 4. The method according to claim 1, wherein when the ratecontrol parameter is received from the non-serving base station, therate control parameter comprises the fourth control state or a fifthcontrol state, the fifth control state indicating maintaining anauthorized traffic-to-pilot power ratio, the method further comprising:updating the second traffic-to-pilot power ratio for the terminal usingthe rate control parameter received from the serving base station aslong as any rate control parameter that is received from the non-servingbase station does not include the fourth control state indicatingdecreasing the first traffic-to-pilot power ratio or the fifth controlstate indicating maintaining the authorized traffic-to-pilot powerratio.
 5. The method according to claim 1, wherein the pilot power ofthe traffic-to-pilot power ratio is controlled by the base station. 6.The method according to claim 1, wherein the rate control parametercomprises a one bit indication.
 7. The method according to claim 1,further comprising: receiving the rate control parameter on a dedicatedcontrol channel.
 8. The method according to claim 1, further comprising:transmitting data on a reverse packet data channel (R-PDCH) at a ratewhich does not exceed the second transmission data rate.
 9. The methodaccording to claim 1, further comprising: updating the secondtraffic-to-pilot power ratio by decreasing the first traffic-to-pilotpower ratio when either the rate control parameter is received from thenon-serving base station and includes the fourth control stateindicating decreasing the first traffic-to-pilot power ratio, or therate control parameter is received from the serving base station andincludes the second control state indicating decreasing the firsttraffic-to-pilot power ratio.
 10. The method according to claim 1,further comprising: updating the second traffic-to-pilot power ratiousing the rate control parameter received from the serving base stationwhen the rate control parameter is not received from the non-servingbase station within a certain period of time.
 11. The method accordingclaim 1, wherein the rate control parameter is set periodically by thenetwork.
 12. The method according claim 1, wherein the rate controlparameter is set non-periodically by the network.
 13. The methodaccording claim 1, wherein the rate control parameter comprises onesymbol.
 14. A method of controlling data transmission rate in a terminalused in a wireless communication system comprising a network, the methodcomprising: providing data to the network at a first data transmissionrate wherein the first data transmission rate is associated with a firsttraffic-to-pilot power ratio; transmitting, to the network, a statusinformation bit on a reverse link to permit generation of a rate controlparameter based upon the status information bit; receiving the firstrate control parameter from a serving base station and a non-servingbase station; determining if a second rate control parameter indicatinga specific data transmission rate has been received, wherein if thesecond rate control parameter has been received, the method furthercomprises: determining a traffic-to-pilot power ratio for the terminalbased upon the second rate control parameter, regardless of whether thefirst rate control parameter has been received from the serving basestation and/or the non-serving base station; otherwise, if the secondrate control parameter has not been received, the method furthercomprises: when the rate control parameter is received from the servingbase station, the rate control parameter comprises a first, second, orthird control state, the first control state indicating increasing thefirst traffic-to-pilot power ratio, the second control state indicatingdecreasing the first traffic-to-pilot power ratio, and the third controlstate indicating maintaining the first traffic-to-pilot power ratio, andwherein when the rate control parameter is received from the non-servingbase station, the rate control parameter comprises a fourth controlstate, the fourth control state indicating decreasing the firsttraffic-to-pilot power ratio; updating a second traffic-to-pilot powerratio of the terminal by decreasing the first traffic-to-pilot powerratio when the rate control parameter is received from the non-servingbase station and includes the fourth control state indicating decreasingthe first traffic-to-pilot power ratio; updating the secondtraffic-to-pilot power ratio for the terminal using the rate controlparameter received from the serving base station as long as any ratecontrol parameter that is received from the non-serving base stationdoes not include the fourth control state indicating decreasing thefirst traffic-to-pilot power ratio; and determining a second datatransmission rate for the terminal based upon the secondtraffic-to-pilot power ratio.
 15. The method according to claim 14,further comprising: determining a value of the status information bitbased on at least one of an amount of reverse link transmission power,buffer status of the terminal, and an amount of data to be transmittedto the network.
 16. The method according to claim 14, wherein the statusinformation bit is based on at least one of a buffer status of theterminal, and an amount of power available to the terminal.
 17. Themethod according to claim 14, wherein when the rate control parameter isreceived from the non-serving base station, the rate control parametercomprises the fourth control state or a fifth control state, the fifthcontrol state indicating maintaining an authorized traffic-to-pilotpower ratio, the method further comprising: updating the secondtraffic-to-pilot power ratio for the terminal using the rate controlparameter received from the serving base station as long as any ratecontrol parameter that is received from the non-serving base stationdoes not include the fourth control state indicating decreasing thefirst traffic-to-pilot power ratio or the fifth control state indicatingmaintaining the authorized traffic-to-pilot power ratio.
 18. A method ofcontrolling data transmission rate in a terminal used in a wirelesscommunication system comprising a network, the method comprising:providing data to the network at a first data transmission rate whereinthe first data transmission rate is associated with a firsttraffic-to-pilot power ratio; transmitting, to the network, a statusinformation bit on a reverse link to permit generation of a rate controlparameter based upon the status information bit; receiving the firstrate control parameter from a serving base station and a non-servingbase station; determining if a second rate control parameter indicatinga specific data transmission rate has been received, wherein if thesecond rate control parameter has been received, the method furthercomprises: determining a traffic-to-pilot power ratio for the terminalbased upon the second rate control parameter and the first rate controlparameter from the non-serving base station, regardless of whether thefirst rate control parameter has been received from the serving basestation; otherwise, if the second rate control parameter has not beenreceived, the method further comprises: when the rate control parameteris received from the serving base station, the rate control parametercomprises a first, second, or third control state, the first controlstate indicating increasing the first traffic-to-pilot power ratio, thesecond control state indicating decreasing the first traffic-to-pilotpower ratio, and the third control state indicating maintaining thefirst traffic-to-pilot power ratio, and wherein when the rate controlparameter is received from the non-serving base station, the ratecontrol parameter comprises a fourth control state, the fourth controlstate indicating decreasing the first traffic-to-pilot power ratio;updating a second traffic-to-pilot power ratio of the terminal, bydecreasing the first traffic-to-pilot power ratio, when the rate controlparameter is received from the non-serving base station and includes thefourth control state indicating decreasing the first traffic-to-pilotpower ratio; updating the second traffic-to-pilot power ratio for theterminal using the rate control parameter received from the serving basestation as long as any rate control parameter that is received from thenon-serving base station does not include the fourth control stateindicating decreasing the first traffic-to-pilot power ratio; anddetermining a second data transmission rate for the terminal based uponthe second traffic-to-pilot power ratio.
 19. The method according toclaim 18, further comprising: determining a value of the statusinformation bit based on at least one of an amount of reverse linktransmission power, buffer status of the terminal, and an amount of datato be transmitted to the network.
 20. The method according to claim 18,wherein the status information bit is based on at least one of a bufferstatus of the terminal, and an amount of power available to theterminal.
 21. The method according to claim 18, wherein when the ratecontrol parameter is received from the non-serving base station, therate control parameter comprises the fourth control state or a fifthcontrol state, the fifth control state indicating maintaining theauthorized traffic-to-pilot power ratio, the method further comprising:updating the second traffic-to-pilot power ratio for the terminal usingthe rate control parameter received from the serving base station aslong as any rate control parameter that is received from the non-servingbase station does not include the fourth control state indicatingdecreasing the first traffic-to-pilot power ratio or the fifth controlstate indicating maintaining the authorized traffic-to-pilot powerratio.
 22. A method of controlling data transmission rate in a terminalused in a wireless communication system comprising a network, the methodcomprising: providing data to the network at a first data transmissionrate wherein the first data transmission rate is associated with a firsttraffic-to-pilot power ratio; transmitting, to the network, a statusinformation bit on a reverse link to permit generation of a rate controlparameter based upon the status information bit; receiving the firstrate control parameter from at least one of a serving base station and anon-serving base station; determining if a second rate control parameterindicating a specific data transmission rate has been received, whereinif the second rate control parameter has been received, the first ratecontrol parameter has been received from the serving base station, andthe first rate control parameter has not been received from thenon-serving base station, the method further comprises: determining atraffic-to-pilot power ratio for the terminal based upon the second ratecontrol parameter, regardless of the receiving of the first rate controlparameter from the serving base station; otherwise, if the second ratecontrol parameter has not been received, the method further comprises:when the rate control parameter is received from the serving basestation, the rate control parameter comprises a first, second, or thirdcontrol state, the first control state indicating increasing the firsttraffic-to-pilot power ratio, the second control state indicatingdecreasing the first traffic-to-pilot power ratio, and the third controlstate indicating maintaining the first traffic-to-pilot power ratio, andwherein when the rate control parameter is received from the non-servingbase station, the rate control parameter comprises a fourth controlstate, the fourth control state indicating decreasing the firsttraffic-to-pilot power ratio; updating a second traffic-to-pilot powerratio of the terminal by decreasing the first traffic-to-pilot powerratio when the rate control parameter is received from the non-servingbase station and includes the fourth control state indicating decreasingthe first traffic-to-pilot power ratio; updating the secondtraffic-to-pilot power ratio for the terminal using the rate controlparameter received from the serving base station as long as any ratecontrol parameter that is received from the non-serving base stationdoes not include the fourth control state indicating decreasing thefirst traffic-to-pilot power ratio; and determining a second datatransmission rate for the terminal based upon the secondtraffic-to-pilot power ratio.
 23. The method according to claim 22,further comprising: determining a value of the status information bitbased on at least one of an amount of reverse link transmission power,buffer status of the terminal, and an amount of data to be transmittedto the network.
 24. The method according to claim 22, wherein the statusinformation bit is based on at least one of a buffer status of theterminal, and an amount of power available to the terminal.
 25. Themethod according to claim 22, wherein when the rate control parameter isreceived from the non-serving base station, the rate control parametercomprises the fourth control state or a fifth control state, the fifthcontrol state indicating maintaining the authorized traffic-to-pilotpower ratio, the method further comprising: updating the secondtraffic-to-pilot power ratio for the terminal using the rate controlparameter received from the serving base station as long as any ratecontrol parameter that is received from the non-serving base stationdoes not include the fourth control state indicating decreasing thefirst traffic-to-pilot power ratio or the fifth control state indicatingmaintaining the authorized traffic-to-pilot power ratio.
 26. A terminalfor use in a wireless communication system comprising a network, theterminal comprising: a transmitter configured to provide data to thenetwork at a first data transmission rate, wherein the first datatransmission rate is associated with a first traffic-to-pilot powerratio, and to provide to the network a status information bit on areverse link to permit generation of a rate control parameter based uponthe status information bit; a receiver configured to receive the ratecontrol parameter from a serving base station and a non-serving basestation; and a processor operatively coupled to the transmitter and thereceiver and configured to control the terminal, wherein when the ratecontrol parameter is received from the serving base station, the ratecontrol parameter comprises a first, second, or third control state, thefirst control state indicating increasing the first traffic-to-pilotpower ratio, the second control state indicating decreasing the firsttraffic-to-pilot power ratio, and the third control state indicatingmaintaining the first traffic-to-pilot power ratio, and wherein when therate control parameter is received from the non-serving base station,the rate control parameter comprises a fourth control state, the fourthcontrol state indicating decreasing the first traffic-to-pilot powerratio, wherein the processor is further configured to: update a secondtraffic-to-pilot power ratio of the terminal by decreasing the firsttraffic-to-pilot power ratio when the rate control parameter is receivedfrom the non-serving base station and includes the fourth control stateindicating decreasing the first traffic-to-pilot power ratio; update thesecond traffic-to-pilot power ratio for the terminal using the ratecontrol parameter received from the serving base station as long as anyrate control parameter that is received from the non-serving basestation does not include the fourth control state indicating decreasingthe first traffic-to-pilot power ratio; and determine a second datatransmission rate for the terminal based upon the secondtraffic-to-pilot power ratio.
 27. The terminal according to claim 26,further comprising: determining a value of the status information bitbased on at least one of an amount of reverse link transmission power,buffer status of the terminal, and an amount of data to be transmittedto the network.
 28. The terminal according to claim 26, wherein thestatus information bit is based on at least one of a buffer status ofthe terminal, and an amount of power available to the terminal.
 29. Theterminal according to claim 26, wherein when the rate control parameteris received from the non-serving base station, the rate controlparameter comprises the fourth control state or a fifth control state,the fifth control state indicating maintaining an authorizedtraffic-to-pilot power ratio, and wherein the processor is furtherconfigured to: update the second traffic-to-pilot power ratio for theterminal using the rate control parameter received from the serving basestation as long as any rate control parameter that is received from thenon-serving base station does not include the fourth control stateindicating decreasing the first traffic-to-pilot power ratio or thefifth control state indicating maintaining the authorizedtraffic-to-pilot power ratio.
 30. The terminal according to claim 26,wherein the pilot power of the traffic-to-pilot power ratio iscontrolled by the base station.
 31. The terminal according to claim 26,wherein the rate control parameter comprises a one bit indication. 32.The terminal according to claim 26, wherein the receiver is furtherconfigured to receive the rate control parameter on a dedicated controlchannel.
 33. The terminal according to claim 26, wherein the transmitteris further configured to transmit data on a reverse packet data channel(R-PDCH) at a rate which does not exceed the second transmission datarate.
 34. The terminal according to claim 26, wherein the processor isfurther configured to: update the second traffic-to-pilot power ratio,by decreasing the first traffic-to-pilot power ratio, when either therate control parameter received from the non-serving base stationincludes the fourth control state indicating decreasing the firsttraffic-to-pilot power ratio, or the rate control parameter is receivedfrom the serving base station and includes the second control stateindicating decreasing the first traffic-to-pilot power ratio.
 35. Theterminal according to claim 26, wherein the processor is furtherconfigured to: update the second traffic-to-pilot power ratio using therate control parameter received from the serving base station when therate control parameter is not received from the non-serving base stationwithin a certain period of time.
 36. The terminal according to claim 26,wherein the rate control parameter is set periodically by the network.37. The terminal according to claim 26, wherein the rate controlparameter is set non-periodically by the network.
 38. The terminalaccording to claim 26, wherein the rate control parameter comprises onesymbol.